Thermal recovery of photocurrent in GaAs with EL2 defects and residual acceptors

We have performed measurements of the thermal recovery of the photocurrent in semiinsulating GaAs after photoquenching at low temperature of the EL2 defects. We find that determination of the thermal regeneration rate parameters from measurements of the photocurrent recovery with use of a linear heating rate requires consideration of the capture of electrons from the regenerated EL2 centers by the initially neutral residual acceptors. An analysis yields E r = 0.34 eV and r 0 = 1.6 × 10 12 s −1 in agreement with values reported in the literature on the basis of infrared absorption measurements. The residual acceptor density is estimated to 2.3 × 10 21 m −3 and the EL2 density to 5.9 × 10 21 m −3.